The invention relates to semiconductor structures and, more particularly, to structures for coupling an optical fiber to an optical waveguide and methods of manufacture.
The use of both photonic devices in high-speed switching and transceiver devices in data communications are but a few examples that highlight the advantages of processing both optical and electrical signals within a single integrated device. For example, an integrated photonic device may include both photonic and complementary metal-oxide-semiconductor (CMOS) type devices that may be fabricated with a single substrate. However, optical signals may need to be efficiently transmitted to and from the integrated photonic device without enduring significant power loss. Moreover, within the integrated photonic device, optical signals may need to be efficiently coupled to a photonic device (e.g., a photodetector) via an optical waveguide residing within the integrated photonic device.
Transmitting light from a light source, such as a laser, across a semiconductor structure, such as an integrated circuit, can be difficult to achieve. For example, sophisticated alignment packaging schemes are needed to align the integrated circuit to an optical fiber. This alignment needs to be accurate to the submicron level, which can be very costly. Also, the diameter of fiber, and a beam of light output by the fiber, can be substantially larger, e.g., by a factor of 200, than the diameter of a waveguide. Because of this large difference in diameter, substantial optical loss often occurs when coupling the fiber to the waveguide.